It is suspected that one mechanism of the pathology of grain worker's pneumoconiosis is allergenic response. Since most allergenic reactions are due to antigens of protein composition and since grains are high protein materials, the most effective method of evaluating grain elevator atmospheres would be through the monitoring of protein particle concentrations and distributions. The objective is to utilize a ninhydrin protein particle staining technique to determine particulate protein concentrations and size distributions in the grain elevator industry and compare these parameters of air contamination to outside ambient conditions. The demonstration of high protein particle concentrations of respirable size would have a direct bearing on the elucidation of the true etiology of grain worker's pneumoconiosis.